Foundations

Before looking at individual genes and markers, start with the basics: what a gene is, how DNA is used to make a protein, and what allele, genotype and inheritance mean. The articles introduce these terms and illustrate selected processes.

18 articles

• What is a gene?From chromosome to DNA to a single gene, the hierarchy of the genome.
• DNA: bases and double helixFour letters, two strands, one twisted ladder.
• Chromosomes and karyotype23 pairs, one from the mother, one from the father.
• Gene structure: exon, intron, promoterA gene is more than its coding sequence.
• From gene to proteinThe central dogma: DNA becomes RNA becomes protein.
• The genetic code64 codons, 20 amino acids, one nearly universal dictionary.
• Allele, genotype and phenotypeGenotype describes alleles; their effects depend on context.
• Dominant and recessiveWhen an allele prevails, and when it takes two.
• Mutation and variantFrom a single letter to a missing piece.
• Inheritance patternsHow traits travel through the family tree.
• Penetrance and expressivityWhy the same genotype is not the same fate.
• Linkage and haplotypeWhy neighbouring variants are inherited together.
• EpigeneticsHow gene activity can change without changing the DNA sequence.
• GWAS and polygenic scoresHow thousands of small effects become a risk value.
• Reference genome and buildsWhat every position is measured against, and why coordinates change.
• TelomeresProtective caps at chromosome ends that shorten with each cell division.
• Reading a genome reportReport CompanionHow to understand genetic reports without overinterpreting findings.
• WGS, SNP test and WESGenomeThree data types, with different coverage and use cases.